As tempting as skipping leg day can be, skipping rest days is even more appealing. For everyone who is highly motivated to excel in their sport or their fitness goals, allowing adequate time for recovery between training can feel impossible. And for those of us who are just getting acquainted with the gym, multiple days marked by muscle pain and weakness can make building good exercise habits extremely difficult. The harsh truth is that regardless of whether you’re a power-lifter, yogi, or avid stationary cyclist, a hard workout requires recovery time. Anything we do that pushes the limits of our strength and endurance causes at least some temporary strain and damage to our muscles, otherwise known as muscle fatigue. If we deny ourselves adequate time to recover between workouts, we can’t perform at our best, and if we skip too many rest days, fatigue can accumulate and put us at heightened risk for injury or overtraining.

In some cases, overtraining can take months or even years to recover from (1). Maximizing recovery efficiency is therefore critical for maximizing training efficiency. That is, if it takes less time for our muscles to recover after exercise, we can reach our goals faster. Red light therapy is an exciting approach to improving recovery time that has become popular among elite athletes and sports professionals and has rapidly gained extensive scientific support over the last decade (1). Studies conducted in both animals and humans have demonstrated red-lights ability to influence the structural and metabolic changes associated with muscle fatigue (2). For example, red light therapy has been shown to reduce post-exercise blood lactate concentration (2). Lactate is a byproduct of the cellular metabolic changes associated with the development of fatigue. As energy demands on the muscle exceed energy production, changes in metabolic processes cause lactate to accumulate around the active muscle. The build-up of lactate is thought to inhibit the ability of the muscle to contract, resulting in a decline in performance (1). A 2011 study that evaluated lactate levels in 6 athletes after a challenging physical test found lower concentrations of blood lactate in athletes who received red-light therapy after the physical test compared to those who didn’t (3).

Similar results have been observed in animal models of muscle fatigue. For example, in a study conducted on the effects of low-level irradiation after exercise, Liu and colleagues (2009)  found reduced levels of inflammation after downhill running tasks in rats that received red light therapy compared to rats that did not (4). During exercise, especially if the activity is new or high intensity, the contraction of muscle fibers can cause microscopic tears in the tissue. These microlesions lead to an inflammatory response that can impair functional recovery and muscle remodeling and, ultimately, can increase the number of rest days you need (5).

Red light therapy has also been shown to reduce oxidative stress, another important biological feature of muscle fatigue (2). As you use your muscles to their maximum capacity, the cellular respiration process begins to produce harmful molecules known as free radicals. The effect free radicals have on your cells is what’s called oxidative stress. Exercise-related oxidative stress can reduce blood flow and can damage the cell’s mitochondria, both of which are critical for muscle recovery (1).

Research into red light’s influence on muscular recovery processes spans different members of the animal kingdom, forms of exercise, and training intensity levels. Across all this variety, post-exercise treatment with red light reliably impacts structural and metabolic processes associated with muscle fatigue (6). By reducing the harmful cellular by-products of exercise, red light therapy can accelerate recovery time. Though precise mechanisms for how red light reduces biomarkers of fatigue are still disputed, one common theory centers around the photosensitive nature of mitochondria. Because red light’s long wavelengths are able to penetrate through the skin and into the muscle tissue with minimal diffusion, it can interact directly with a cell’s light-reactive mitochondria (2). As you likely know, mitochondria are the “powerhouses” of the cell, meaning one of their main functions is to produce the energy that cells require to operate efficiently. Red light is thought to improve cellular respiration and energy-synthesis in mitochondria, which allows them to boost overall cellular function (2). By accelerating the cellular processes required for recovery, red light can facilitate full muscle recovery in less time.

For professional athletes and home-workout enthusiasts alike, optimal performance necessitates a balance between hard work and recovery time. The process of building strength and endurance is taxing all the way down to a cellular level, which is why our bodies require adequate rest. The amount of time required for recovery is thus a major limiting factor in how quickly we can arrive at our fitness and athletic goals. Red light therapy is a safe and scientifically supported approach to achieving maximum recovery in minimal time. Whether you’re just starting to build fitness habits or you’re training to dominate in competitions, red light therapy might be a great choice for you.

Resources:

  1. Forsey, Jillian Danielle (2020). The Effects of Acute Photobiomodulation on Anaerobic Exercise Performance. Graduate Theses, Dissertations, and Problem Reports. 7529. Link
  2. Ferraresi, C., Hamblin, M.R., & Parizotto, N.A. (2012). Low-level laser (light) therapy (LLLT) on muscle tissue: performance, fatigue, and repair benefited by the power of light. Photonics and lasers in medicine. 1(4):267-286. Link
  3. Leal Junior EC, de Godoi V, Mancalossi JL, Rossi RP, De Marchi T, Parente M, Grosselli D, Generosi RA, Basso M, Frigo L, Tomazoni SS, Bjordal JM, Lopes-Martins RA. Comparison between cold water immersion therapy (CWIT) and light-emitting diode therapy (LEDT) in short-term skeletal muscle recovery after high-intensity exercise in athletes – preliminary results. Lasers Med Sci 2011;26(4):493–501. Link
  4. Liu, X.G., Zhou, Y.J., Liu, T.C., & Yuan, J.Q. (2009). Effects of low-level laser irradiation on rat skeletal muscle injury after eccentric exercise. Photomedicine and Laser Surgery. 27(6):863-869. Link
  5. Peak, J., Neubauer, O., Della Gatta, P., & Nosaka, K. (2016). Muscle damage and inflammation during recovery from exercise. Journal of Applied Physiology, 122: 559-570. Link
  6. Leal-Junior, E.C.P (2015). Photobiomodulation Therapy in Skeletal Muscle: From exercise performance to muscular dystrophy. Photomedicine and Laser Surgery, 33(2). 53-54. Link
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